Injection of fuel in internal-combustion engines.



J. McKECHNIE.

INSECTION 0F FUEL IN INTERNAL comausnow ENGINES.

APPLICATION FILED DEC. 2 1916. m fififiwa Patented May 14, 1918.

J MOKECHNIE, OF BABROW-IN-FURNESS, ENGLAND, ASSIGNOR TO VICKEBS LIMITED,OF WESTMINSTER, ENGLAND. 1

INJECTION 0F FUEL 1N INTERNAL-COMBUSTION ENGINES.

Application filed December 2, 1916.

To all whom it may concern:

Be it known that I, JAMES McKncnNm, a subject of the King of GreatBritain, residing at Naval Construction Works, Barrow-in-Furness, in thecounty of Lancaster, England, have invented certain new and usefulImprovements in or Relating to the Injection of Fuel inInternal-Combustion Engines, of which the following is a specivalvelever controlling the fuel injection is' operated by a cam the outlineof which is so formed with relation to the path given by variation ofthe lever adjustment to the extremity of the lever that, for allclearances between the cam and lever and resulting variation in durationof fuel injection and engine power, the valve is timed to'open at thecorrect point at which injection should take place, without theintroduction of special timing mechanism.- For this purpose thedisplacement of the lever for varying the fuel injection must be sochosen that a cam surface giving the correct timing for the variablespeed and quantity of fuel is one of practicable form. r

A convenient method of adjusting the lever is to mount its fulcrum uponan eccentric partially rotatable so as to move the cam roller at the endof the lever toward or away from the cam and also usually to'displace itforwardly or rearwardly of the cam.

It has not hitherto been realized that a lever adjustment and the camoutline could be so related as togive the best timing of the .valveopening for all variations in engine power, but it is now found that bysuitably choosing the size of the eccentric upon which the fuel leverfulcrum is mounted, the direction of partial rotation of the eccentricand the portion of the path of the eccentric during which regulation ofthe fuel valve is effected, the necessary movement of the fuel valvelever roller away from the cam cm be accomplished by any desiredmovement- Specification of Letters Patent.

Patented May 14:, 1918.

Serial No. 134,642. i

of the lever roller in or against the direction of rotation of the cam,and it is thus possible to obtain the required opening and closing of ithe fuel valve at all adjustments without departing to any materialextent from the cam profile most suitable for any particular duty of theengine.

The following edge of the cam is of course shaped in accordance with theform of the leading edge to give the proper duration of injection forall adjustments of the valve lever. This duration in an engine usingmechanical injection and fuel supplied at constantpressure (for exampleby a battery of pumps passing any surplus fuel through a relief valve)will determine the charge of fuel at each firing stroke and willtherefore depend upon the purpose of the engine. Thus in a marine engineof this type the angle of duration for a given reduced charge will,owing to the greater time of opening at lower speed, be less than in aconstant speed dynamo engine. In an engine in which mechanical injectionis used and a measured quantity of fuel is supplied at each firingstroke the angle of duration of opening will be so arranged that thespraying pressure is maintained at a high level even at low powers ofthe engine. In an engine using compressed air for the pulverization andspraying of the fuel the reduction of duration will be such as toprevent wastage of air owing to the valve remainin open longer ghap isnecessary for the in ection of the The partial rotation of theeccentrically mounted fulcrum bearing of the fuel valve lever may beeffected simultaneously with thecontrol of the fuel pump. Thus in aconstant speed engine with a surplus fuel ing the two adjusting-gears,be made to give to'the injection valve the correct functionsfor thepower as determined by the quantitydelivered by the fuel pump. For thispurpose, we may mechanically operate the suction valve of'the pump bymeans of acam and adjustable lever with variable clearance on the linesdescribed above for the injection valve lever. The displacement of thelever and the cam profile will in this case he so correlated that thesuction valve may open early in the suction stroke or the pump at alladjustments and will close, according to the adjustment, at any pointwithin the desired range of the delivery strolre of the pump asuiiicient lift of the valve being given at all adjustments.

in order that the said invention may he clearly understood and readilycarried into efiect the same will he described more fully with referenceto the accompanying drawings in which i urc 1 shows the application ofthe invention to the fuel injection valve operating devic of a constantspeed internal combustion engine such as a dynamo engine,

Fl 2 shows the application of the i ention t 11 fuel injection valveoperatin levice of a va iahle speed engine such as a marine engine 3shows the application of the invention to the gear operating the suctioni of the high pressure fuel pump an internal combustion engine; and

Fig. i is an enlarged view of shown in 3.

A is the earn shaft oi the engine upon which are mounted the injectionvalve cares U or C" and, 1 igs. 3 and 1-, the pump earn C is the valvespindle of the fuel injeca detail tion valves is the injection valveoperating lever mounted on the eccentric or crank ll of the fulcrum pinl which can he partly rotated about its center and so move the center72, of the eccentric The lever oscillates about this center it and, asthe tulcruin pin is partly rotated, the eccentric cener it e ves in areabout the pin ceni the cam roller on the end of the revolving about itscenter 6. g

lever shows the position at which the valve end of the lever touches thevalve spindle when the valve is closed. it is the center of theeccentric H in maximum power position and c is the correspondingclearance hetween the oller and cam C l} or cani 2). q

Referring to Fig. 1., which shows the application of the invention to aconstant speed engine in which it is desirable to adl u el at an earlystage at all ranges of power the angle a. is the duration oi opening ofthe injection valve when the center of the eccentric H is in its maximumpower position 7;. Upon partial rotation of the tulcruntF in a directionwhich causes the roller D to move opposite to the direction of motion ofthe earn C, the center it moves in an arc to, say, position it, causingboth tangential and radial displacement of th roller in respe to thepath of coin G position g of the valve end of the lever E remaining thesame, that is, the valve is still closed), so that the center 2 of theroller D moves to the position 8, increasing the clearance loctween thecam C and the roller D to c. The duration of opening of the injectionvalve is now given by the angle a. @wing to the radial component 6 a ofthe displacement of the roller D which now works on the higher part ofthe cam C, the opening of the fuel valve is delayed by an amountrepresented h v the angle 7) between the points 6 and e 6 losing thecenter ot a circle of the same diameter as D and touch ing the circle ofclearance c and the cam Q. But in moving from center a to center 6 theroller D has had imparted to it a tangential or angular displacement Z)partly conipensating for the delay in the opening of the fuel valve dueto the roller working on the higher part of the cam. The net delay inthe opening oi the valve is therefore the small angle represented by Z'-b, i. c. the angle subtended at the center of the cam shaft by thedistance e"-e the extreme case in which the opening the fuel valve hasto take place at the same point for all powers the path through whichthe center of the roller D is moved by the partial rotation of the pin Fwould be made to follow as closely as possible the contour of theleading face of the cam Q making the angle a' a zero. This may incertain cases entail inconvenient proportions of the eccentric H and inorder to avoid this the leading edge of the cam may he made as steep aspracticable so as to reduce the delay in opening of the fuel valve dueto the roller worlringon the higher part of the cam. ln practice aslight retardation of the admission of fuel is desirable at reducedpowers and this retardation is efiected by gradually sloping the leadingedge of the cam C as shown in l.

The position a shows the center of the roller l) for the cut outposition 72, of the eccentric H when the roller is quite clear of thecam Q Referring Fin. 2, which shows the application oi the invention toa variable speed engine in which as the power fails it is desirable toretard the fuel injection to considerably greater extent than in aconspeed engine, the angle a is the duraticn cl" opening-of the fuelinjection valve when the center of the eccentric H is in its maximumpower position 7L. Upon partial rotation of the fulcrum pin F, in adirection, such that the roller D moves in the same direction as the camC, the center 72 moves to, say position if. This causes both atangential and radial displacement of the roller l) relatively to thepath of the cam C (the no sition g the valve end of the lever iei thesaine that is the valve is still closed), the center of the roller Dmoving to the position 6 increasing the clearance 0 between the cam Cand the roller D to 0 so that the duration of opening of the fuelinjection valve becomes a owing to the radial displacement 6-6 of theroller D, which now works on the higher part of the cam C, and, due tothis radial displacement only, the opening of the fuel valve is delayedby an amount represented by the angle 6 extending from e to e, a beingthe center of a circle of the same diameter as D and touching the circleof clearance c and the cam C. But in moving from the center 6 to center6 the roller D has had imparted to it a tangential displacement b sothat the timing of the opening of the fuel injection valve is delayed bythis amount in addition to the delay due to the roller working on thehigher part of the cam. The total delay in opening is thereforerepresented by a the angle b b It is evident that by suitably choosinthe eccentricity of the eccentric or crank the direction of partialrotation of the fulcrum pin F during regulation and the mean position ofthe line f, h, it is possible to give, during the desired radial motionof the center 6, a tangential motion to the lever E of any desiredamount in either direction, so that with a cam of practicable shape itis possible at all powers to obtain a close approximation to the desiredpoint of opening of the fuel valve.

The path during regulation of the roller D and the leading edge of thecam C or C having been designed conjointly to obtain the requiredvariation of timing of the first admission of fuel at various powers,the following edge of the cam is arranged relatively to the leading edgeso that the angle of duration a (Fig, 1) or a (Fig. 2) will, in anengine arranged for mechanical injection of fuel at constant pressure,correctly determine the quantity of fuel admitted at each firing stroke,or, alternatively, will, in an engine arranged with fuel measuringpumps, maintain the injection pressure at a high level at all powers. Ina constant speed engine the angle of duration of injection willobviously be greater for a given power than in, say, a marine engine.

In carrying the invention into effect it will be necessary to insurethat the practical area for flow through the injection valve is normallyconsiderably greater than the practical area through the pulverizingorifices, as is usual, otherwise at intermediate powers there will occurundue restriction before the fuel reaches the pulverizer, thus affectingthe spraying of the fuel. At very low powers partial throttling by theinjection valve may be adopted.

Fig. 3 shows the invention arranged for the control of a pump supplyinghigh pres &

sure fuel oil, where separate fuel pumps are fitted to each cylinder,the control to be effected simultaneously with, and at all adjust-mentsof, the fuel injection valve as already set forth.

P is the fuel oil pump, with suction port S, and suction valve V, whichis controlled by the cam C on the cam shaft A through the cam roller Ron the end of the lever L and the push rod 1). This push rod '2; keepsthe lever L hard up to the cam C by means of the spring 12 through theguide '0'. Y is the fuel injection valve body in the cylinder cover Z,the fuel oil being delivered from the pump P to thefuel injection valveY by means of the pipe 0, in which may be fitted a pressure accumulatorT. M is the hand or governor controlled rock shaft carrying theeccentric N upon which the lover L is mounted. Upon this shaft is alsomounted the lever Z controlling the adjustment of the fuel injectionvalve Y through the link Z and the lever Z on the eccentric fulcrum pinF. V

Fig. at is an enlarged'view of part of the cam C and the roller R on theend of the lever L. The cam C is shown just opening the suction valve Vwhen the rock-shaft M is in its maximum power posit-ion, and the plungerp of the fuel pump P, which is driven from the cam shaft A by aneccentric X, is just commencing to ascend on its suction stroke, so thatn is the position of the center of the eccentric N when it is theposition of the center of the eccentric H, and r is the position of thecenter of the roller R. Upon the rock-shaft M being partly rotated so asto bring the center it of the eccentric H to say hfthe center n of theeccentric N moves in an are about the center of the rockshaft M to theposition it, and in doing so moves the lever L so as to displace theroller R both tangentially and radially. relatively to the path of thecam C the point 9 of the lever L remaining in the same positionthroughout the movement, so that the center r of the roller R takes upthe position 9" shown in Fig. 4. The angular displacement is shown at band this is so proportioned in conjunction with the leading or openingedge of the cam C that the valve V opens at an early point in thesuction stroke of the pump at all adjustments.

The radial displacement of the roller R causes the valve to open withmore or less lift according to the direction of displace.

ment, and in the position 7 the valve obtains its minimum lift Whileinposition r it remains completely open, corresponding to the cut-outposition.

The cam C has its remaining contour so formed that the suction valve Vis held open till the downward stroke of the plunger p begins and thenis allowed to close, the point of closing, depending upon the positionof the center of the eccentric ll, being represented by the angularpositions (3;, Q the positions n, n at, of the said center The curve ofthe closing edge of the cam may he errange so that the efiectivedischarge of the pump bears any desired ratio to the duration of openingof the valve It is thus possible to maintain it high spraypressure atall powers.

l fiat I claim and desire to secure by Let-= ters Patent is 1. Fuelinjecting mechanism for internal combustion engines, comprising aninjection valve, a valve lever, a lever operating cam, and an adjustableeccentric fulcrum for the said lever, so positioned that its path of ad"justinent is approximately tangential to the cam and causes hot-h radialand tangential adjustment of the cam end of the lever, outline of thecan being so formed with re lation to the path of adjustment of thelever end that correct timing of the point at which the valve opens isobtained for ell adjustments,

2, Fuel injecting mechanism for internal combustion engines, comprisingan injection valve, avalve lever, a lever operating cani and anadjustable fulcrum for the lever so positioned that on adjusting thefulcrum for cover regulation the cam end 0" the lever following ed e ofthe cam,

moves along a pa suhstantie iv the contour the J 2-7 where the opdiiierent positions of the engine strolls for lever.

53. Fuel injecting mechanism for internal combustion engines, comprisingan injection valve, an adjustable valve lever, a lever operating camhaving the outline of its leading surface so related the path or"adjustvalve, a valve lever, an adjustable eccentric v fulcrum on whichthe said lever is mounted, a lever operating esin having the outline ofits leading surface so related to the path of adjustment of the lever asto time the valve opening for all adjustments of the lever, a fuel pumpincluding a suction valve, a suction valve cain, cam lever operating thesuction valve, adj ustahle eccentric fulcrum for the said cain lever,and an open etive connection between the two adjustable tulcrums bywhich simultaneous adjustment of the two lovers is effected.

In testimony whereof, l hereto ai'fin my signature,

